Such air-conditioners are generally known in the art. In general, an air-conditioner of this type comprises an outdoor unit (heat source unit) comprising at least the compressor and the heat source heat exchanger of the air conditioner. Depending on the premises to be conditioned, different outdoor units having different capacity and/or using different heat sources (e.g., air, water, etc.) are available. These outdoor units are manufactured and offered on the market by a variety of companies including Daikin®. As the premises (e.g., a building) and, hence, the specifications for the air conditioners vary to a large extent, a plurality of different outdoor units need to be manufactured and be held available by the companies involving relatively high costs. In addition, the present outdoor units are relatively large and heavy so that the locations for installation of these outdoor units are very limited. Even further, in many cases, the optimum capacity and/or efficiency of the outdoor unit cannot be realized with the result of compromise with overcapacity and/or reduced efficiency of the air conditioner.